Lens barrel, photographic device, and production method of same

ABSTRACT

A lens barrel comprising bayonet type mount projections to detachably attach to a lens-fitting unit of a camera body having a photographic region, wherein mount projections are formed to avoid cross-section of light path area where object light is introduced in the camera body.

This is a Divisional of U.S. patent application Ser. No. 11/724,191filed Mar. 15, 2007. The disclosure of the prior application isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a lens barrel, a photographic deviceand production methods of the lens barrel and the photographic device.

2. Description of the Related Art

In the Japanese Unexamined Patent Publication (A) No. 2000-121904, alens barrel is proposed to enable to change a diaphragm to cut offharmful rays in accordance with the size of the image circle. However, aprior lens barrel cannot reduce effects of catoptric light due tobayonet mounts.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a lens barrel and acamera system enabling to reduce effects of catoptric light.

A lens barrel according to a first aspect of the present inventioncomprises

a barrel holding an optical system, and

a barrel-side mount fitting said barrel on a photographic device havingan imaging unit, wherein

said imaging unit takes an image formed on a rectangular imaging planeby said optical system, and said barrel-side mount is placed in theposition to avoid corners of said rectangular imaging plane.

A lens barrel according to a second aspect of the present inventioncomprises

a barrel holding an optical system,

a barrel-side mount to fit said barrel to a photographic device, and

two or more barrel-side electric contact groups, wherein

said photographic device comprises an imaging unit to take an image,number of said barrel-side mounts are present, and each of saidbarrel-side electric contact groups includes two or more electriccontact points and is placed with a space between each other barrel-sideelectric contact groups.

A lens barrel according to a third aspect of the present inventioncomprises

a barrel holding an optical system,

a barrel-side mount to fit said barrel to a photographic device, and

two or more barrel-side electric contact points, wherein saidphotographic device comprises an imaging unit to take an image, and saidbarrel-side mount is placed between said barrel-side electric contactpoints.

A lens barrel according to a forth aspect of the present inventioncomprises

a barrel-side fitting unit placed detachably-attached to a body-sidefitting unit of a camera body having a photographic region, and

a barrel-side mount projection, which is formed at more than one pointalong the circumferential direction of said barrel-side fitting unit,set in opening site of said body-side fitting unit and engaged with abody-side mount projection formed at more than one point along thecircumferential direction of said body-side fitting unit to prevent fromreleasing, wherein

at least said barrel-side mount projection is formed on said barrel-sidefitting unit to avoid cross-section of light path area where objectlight is introduced in said camera body.

A lens barrel according to a fifth aspect of the present inventioncomprises

a bayonet unit arranged to a camera body having a photographic region toretain, wherein

said bayonet unit is arranged to avoid light flux entering in saidphotographic region among light flux going to the side of saidphotographic region.

A photographic device according to a first aspect of the presentinvention comprises

an imaging unit to take an image formed on a rectangular imaging planeby an optical system, and

a photographic device-side mount to fit a lens barrel to saidphotographic device, wherein

said lens barrel has said optical system, and said photographicdevice-side mount is placed to avoid corners of said rectangular imagingplane.

A photographic device according to a second aspect of the presentinvention comprises

an imaging unit to take an image by an optical system,

a photographic device-side mount to fit a lens barrel to saidphotographic device, and

two or more photographic device-side electric contact groups, wherein

said lens barrel has an optical system to form an image on said imagingplane,

each of said electric contact groups has two or more contact points, andis placed with a space between each other photographic device-sideelectric contact groups.

A photographic device according to a third aspect of the presentinvention comprises

an imaging unit to take an image by an optical system,

a photographic device-side mount to fit a lens barrel to thephotographic device, and

two or more photographic device-side electric contact points, wherein

said lens barrel has said optical system to form an image on saidimaging plane, and

said photographic device-side mount is placed between said photographicdevice-side electric contact points.

A production method of the lens barrel according to a first aspect ofthe present invention comprises the steps of:

providing a barrel holding an optical system, and

providing a barrel-side mount that fits a photographic device to saidbarrel, wherein

said photographic device comprises an imaging unit,

said imaging unit comprises a rectangular imaging plane,

said imaging unit takes an image formed on said rectangular imagingplane by said optical system, and

said barrel-side mount is placed to avoid corners of said rectangularimaging plane.

A production method of the lens barrel according to a second aspect ofthe present invention comprises the steps of:

providing a barrel holding an optical system,

providing multiple barrel-side mounts on said barrel to fit aphotographic device having an imaging unit to take an image formed bysaid optical system, and

providing two or more barrel-side electric contact groups, each of whichis placed with a space between each other and has two or morebarrel-side electric contact points.

A production method of the lens barrel according to a third aspect ofthe present invention comprises the steps of:

providing a barrel holding an optical system,

providing a barrel-side mount on said barrel to fit a photographicdevice having an imaging unit to take an image formed by said opticalsystem, and

providing two or more barrel-side electric contact points, saidbarrel-side mount being placed between said barrel-side electric contactpoints.

A production method of the photographic device according to the firstaspect of the present invention comprises the steps of:

providing an imaging unit having a rectangular imaging plane to take animage formed on said rectangular imaging plane by an optical system, and

providing a photographic device-side mount to fit a lens barrel to theposition to avoid corners of said rectangular imaging plane.

A production method of the photographic device according to the secondaspect of the present invention comprises the steps of:

providing an imaging unit to take an image formed by an optical system,

providing multiple photographic device-side mounts to fit a lens barrel,and

providing two or more photographic device-side electric contact groups,each of which is placed with a space between each other and has two ormore electric contact points.

A production method of the photographic device according to the thirdaspect of the present invention comprises the steps of:

providing an imaging unit to take an image formed by an optical system,

providing a photographic device-side mount to fit a lens barrel, and

providing two or more photographic device-side electric contact points,said photographic device-side mount being placed between saidphotographic device-side electric contact points.

A camera body according to the present invention comprises aphotographic region,

a mirror box to introduce subject light through light path area havingpredetermined cross-section to said photographic region, and

a body-side fitting unit to detachably attached to a barrel-side fittingunit of a lens barrel, wherein

a body-side mount projection to engage with said barrel-side mountprojection formed at least on a part of the circumferential direction ofopening site where a mount projection of said lens barrel is introducedin said body-side fitting unit, and

said body-side mount projection is formed to avoid the cross-section ofsaid light path area.

A camera system according to the present invention comprises the abovelens barrel.

The present invention can provide a lens barrel enabling to reduceeffects of catoptric light and a camera system including said lensbarrel. In the present invention, an object to reduce effects ofcatoptric light is achieved by changing the arranged position or thesize of bayonet mount projections.

BRIEF DESCRIPTION OF THE DRAWINGS

Below, the present invention will be explained in detail based on theembodiments illustrated in the figures, wherein

FIG. 1 is a perspective view of a lens barrel of an embodiment of thepresent invention.

FIG. 2 is a perspective view of a camera body of an embodiment of thepresent invention.

FIG. 3 is a cross-sectional view of the principal parts along an opticalaxis showing the inside of the camera body in FIG. 2 where the lensbarrel in FIG. 1 is fitted, and a cross-sectional view of line III shownin FIG. 4A.

FIG. 4A is a cross-sectional view of the principal parts along lineIVA-IVA in FIG. 3.

FIG. 4B is a cross-sectional view of the principal parts along lineIVB-IVB in FIG. 4A.

FIG. 4C is a view showing a frame format of a lens barrel and an imagingdevice, and an arranged position of mount projections.

FIG. 5 is a cross-sectional view of the principal parts along an opticalaxis showing the inside of the camera body where a lens barrel accordingto a comparative example of the present invention is fitted, and across-sectional view of line V in FIG. 6.

FIG. 6 is a cross-sectional view of the principal parts along line VI-VIin FIG. 5.

FIG. 7-FIG. 10 are cross-sectional views of the principal partscorresponding to FIG. 4A showing the inside of the camera body whereeach lens barrel according to other embodiments of the present inventionis fitted.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

As shown in FIG. 1 and FIG. 2, a lens barrel-type imaging equipmentrepresented by single-lens reflex camera typically includes a lensbarrel 10 and a camera body 30. A lens barrel-side fitting part 11 heldon the back of the lens barrel 10 is detachably attached to a body-sidefitting part 60 held on the front of the camera body 30.

To the inside of a barrel body of a lens barrel 10 shown in FIG. 1,multiple optical lens groups (not shown in the figure) are attachedmovably in the direction of an optical axis. As shown in FIG. 3, acamera body 30 holds a low-pass filter 31 and an imaging device 32. Theimaging device 32 includes magnifying-type solid-state image sensingdevices such as CMOS other than CCD.

A reason to provide a low-pass filter 31 is following. In the imagingdevice 32 of the camera body 30, a phenomenon called a false color or acolor moire can occur resulting in a different coloring from an actualone when a light with high spatial frequency enters in a single pixel ofthe imaging device 32. This phenomenon can be reduced by setting thelow-pass filter 31 at an object side of the imaging device 32.

As shown in FIG. 3, to the inside of the camera body 30, a mirror box 40is attached at a predetermined position relative to body frames 30 a and30 b of the body 30. The imaging device 32 and the low-pass filter 31are attached to the body frame 30 b at a predetermined position. Notethat a body frame 30 c is attached to the back of the imaging device 32.

A mirror not shown in figures is placed in the mirror box 40, whichleads an object light entering parallel to an optical axis in thedirection of a finder when not taking pictures; and Which leads anobject light in the direction of the imaging device 32 by moving themirror when taking pictures.

As shown in FIG. 4A, the imaging device 31 is rectangular in shape Whenviewing vertically from an optical axis L1, which is smaller than arectangular cross-section of an inner opening site 40 a of the mirrorbox 40. A cross section of an inner opening site of a body frame 30 bshown in FIG. 3 is rectangular as well as that of the inner opening site40 a of the mirror box 40. On the other hand, a cross-section of aninner opening site of a body frame 30 a positioned at the object side inthe direction of the optical axis L1 of the mirror box 40 is circular.To the front of the body frame 30 a, a ring-shaped body-side fittingpart 60 is attached.

As shown in FIG. 1 and FIG. 4 b, the barrel-side fitting part 11 held onthe back of the lens barrel 10 is ring-shaped in the Whole toaccommodate the shape of the lens barrel 10. On the barrel-side fittingpart 11, a barrel-side fitting plane 14 is formed substantially verticalto an optical axis L1 of an optical lens group. The barrel-side fittingplane 14 can be attached tightly to a body-side fitting plane 64 formedon a body-side fitting part 60 of a camera body 30. The body-sidefitting plane 64 is also substantially vertical to the optical axis L1of the optical lens group.

Both of the barrel-side fitting part 11 and the body-side fitting part60 are made of metal, and can be detachably attached in the so-calledstyle of a bayonet mount. That is, as shown in FIG. 4A, threebarrel-side mount projections 12 are formed at unequal intervals in thecircumferential direction on the imaging surface side in the directionof the optical axis in the barrel-side fitting part 11.

As shown in FIG. 4B, barrel-side mount projections 12 are extended outradially from a cylindrical inner circumference face 15 of thebarrel-side fitting part 11. Three barrel-side mount projections 12arranged along the circumference as shown in FIG. 4A are connected inthe circumferential direction by a cylindrical stiffened member 16. Theradial thickness of the cylindrical stiffened member 16 is approximatelya half or smaller of the radial width of the mount projections 12.

As shown in FIG. 2 and FIG. 4B, body-side mount projections 62 areformed on the inner circumference face of the body-side fitting part 60at the position corresponding to the barrel-side mount projections 12 atunequal intervals in the circumferential direction. The inner diameterof the body-side mount projection 62 is equal to or slightly larger thanthe outer diameter of the cylindrical stiffened member 16. The outerdiameter of the barrel-side mount projection 12 is slightly smaller thanthe inner diameter of the body-side fitting part 60 without body-sidemount projections 62.

The lens barrel 10 in FIG. 1 is fitted to the camera body 30 in FIG. 2as follows: the mount projections 12 in the barrel-side fitting part 11shown in FIG. 1 are pressed into the inside of the body-side fittingpart 60 at the position in the circumferential direction where body-sidemount projections 62 shown in FIG. 2 are not formed.

After that, the lens barrel 10 is rotated around the optical axis L1 toput the mount projections 12 of the barrel-side fitting part 11 in theimaging surface side of the body-side mount projections 62 of thebody-side fitting part 60 where the lens barrel 10 is fitted to thecamera body 30 in the bayonet-type.

As shown in FIG. 4A and FIG. 4B, a circular-shaped electric contactholding member 70 is fixed on the imaging surface sides in the directionof the optical axis of the cylindrical stiffened member 16 of thebarrel-side fitting part 11 and the mount projections 12. The electriccontact holding member 70 is comprised of an insulating member such asplastic, and two or more barrel-side electric contact points 72 may beplaced on the outer circumferential face of the holding member 70 forexample. These barrel-side electric contact points 72 are detachablyconnected by rotation to each body-side electric contact point 74 placedon the inner circumferential face of a body frame 30 a.

In the present embodiment, the electric contact holding member 70 isfixed at the barrel-side fitting part 11 as shown in FIG. 4A so that themost of the holding member 70 is above the upper long side of an inneropening site 40 a with a rectangular cross-section in the mirror box 40.When fixing the electric contact holding member 70 at the barrel-sidefitting part 11, at least barrel-side electric contact points 72 has tobe placed above the upper long side of the inner opening site 40 a witha rectangular cross-section.

Further, as shown in FIG. 4A, three barrel-side mount projections 12 areplaced at unequal intervals in the circumferential direction so as tosatisfy the following relationship: one of three barrel-side mountprojections 12 is above (outside) the upper long side of the inneropening site 40 a with a rectangular cross-section, another mountprojection 12 is outside the right short side of the inner opening site40 a, and the last mount projection 12 is below (outside) the lower longside of the inner opening site 40 a. It means that the mount projections12 placed on the lens barrel 10 are not exposed at four corners 11 a, 11b, 11 c and lid of the opening site 40 a where only the cylindricalstiffened member 16 is exposed.

Note that the arranging position in the circumferential direction of thebody-side mount projection 62, which forms a bayonet structure in pairswith the barrel-side mount projection 12, is same as that of thebarrel-side mount projection 12.

As shown in FIG. 5 and FIG. 6, in a lens barrel 20 according to acomparative example of the invention, three barrel-side mountprojections 22 are placed at equal intervals on the barrel-side fittingpart 21 regardless of the shape of the cross-section of the inneropening site 40 a in the mirror box 40. Therefore, as shown in FIG. 6, apart of the mount projection 22 placed on the lens barrel 20 is exposedat four corners 21 a, 21 b, 21 c and 21 d of the opening site 40 a whenViewing the direction of the lens barrel 20 from a low-pass filter 31.The mount projections 22 are exposed at two of the four corners, 21 aand 21 b, and the exposed area is large.

The light 50 passing through the inside of the lens barrel 20 can passthrough the low-pass filter 31 to enter an imaging device 32, or can bereflected on the face of the low-pass filter 31 instead of passingthrough it.

Usually, this catoptric light hits the inner surface of the camera body30 or the lens barrel 20, diffuse to fade, or be absorbed, but in rarecases, it can enter the imaging device 32 after reflecting again on theend face of the bayonet-type mount projection 22 placed on the lensbarrel 20. This second catoptric light can hit at the inner surface ofthe camera body 30 if reflecting regularly on the end face of thebayonet-type mount projection 22, but actually, it rarely reflectsregularly since there is microasperity on the end face of the mountprojection 22 due to machine process.

When the second catoptric light 52 b and 52 c enter the imaging device32, it is possible to become a ghost or a flare to deteriorate picturequality. Note that the light ray 50 can reflect on the imaging device32, and also in the case of a silver salt film camera, on the surface ofthe film. In the end face in the optical axis direction of thebarrel-side fitting part 21, the projection 22 has a broader width inthe radial direction, where more catoptric light may hit to easilyincrease ghosts and flare.

Therefore, in the present embodiment, the above-described configurationsof the bayonet-type mount projections 12 and 62 solve the aboveproblems. Hereinbelow, the arranged position of the mount projections 12will be explained. An explanation on the mount projections 62 will beskipped since they have the same arranged position as the mountprojections 12.

As shown in FIG. 4C, the mount projections 12 are arranged to avoid thevicinity of four corners 11 a, 11 b, 11 c and 11 d of a light flux Lwith a rectangular cross-section that goes from the lens barrel 10 toenter the imaging device 32. Actually as shown in FIG. 4A, the mountprojections 12 are arranged not to overlap four corners of the openingsite 40 a. Therefore, the mount projections 12 are not on the diagonalline of the low-pass filter 31, and not exposed on the inside of theopening site 40 a.

When viewing the lens barrel 10 from the low-pass filter 31, fourportions of the barrel-side fitting part 11 placed on the lens barrel 10are exposed at four corners 11 a, 11 b, 11 c, and 11 d of the openingsite 40 a as shown in FIG. 4A. However, the exposed area is small andthe effect of the catoptric light is low since the exposed portions arenot the mount projections 12.

As the mount projections 12 are not exposed on the inside of the openingsite 40 a, the catoptric light 51 from the low-pass filter 31 does notenter the mount projection 12 as shown in FIG. 3. Therefore, the effectof catoptric light to reflect on the mount projection 12 can be reducedto prevent flares and ghosts and to minimize image degradation.

Further, when the lens barrel 10 is a bright optical lens barrel with Fvalue of 2.8 or less, a telephoto lens barrel, or a large diameter lensbarrel for instance, light passes right next to the barrel-side fittingpart 11 causing that the catoptric light easily affects, and therefore,it is meaningful to prevent the catoptric light from entering the mountprojection 12. Also, the effects of the present embodiment are moresignificant when the distance between the imaging device and the mountprojections are closer, e.g. when the imaging device is large (e.g. 24mm×36 mm or larger), or when the diameters of the barrel-side fittingpart 11 and the body-side fitting part 60 are small.

Also, a coating material is applied on components such as a lens holdingrim inside the lens barrel 20 (See FIG. 5 and FIG. 6). However, thecoating may peel off to adhere to the lens or the low-pass filter 31 ifapplying it on the exterior of the barrel-side fitting part 21 that isrubbed when fitting the lens barrel 20 and the camera body 30. It isalso unfavorable to apply a coating only on the mount projection 22 toprevent reflection, which is a protruding portion and may be easilyrubbed and pealed off while removing the lens barrel 20 from the camerabody. However, in this embodiment, it is possible to obtain goodcharacteristics as the configuration of the mount projections 12 and 62prevents reflection instead of applying any coating.

Second Embodiment

As shown in FIG. 7, in a lens barrel 10-2 according to the secondembodiment in the invention, the bayonet-type mount projection 12 hasthe same arranged position as the mount projection 22 according to thecomparative example shown in FIG. 6. However, a notch 13 is formed onthe mount projection 12 a so as to avoid the inner opening site 40 a ofthe mirror box 40 in the lens barrel 10-2 in the present embodiment.

The second embodiment has advantages that it is easy to design andunnecessary to change in basic configuration of a bayonet-type mountprojection 62 of the camera body 30 since the mount projections 12 canbe arranged at equal intervals in the circumferential direction. Otherconfiguration and effects in the present embodiment is same as in theabove-described first embodiment.

Third Embodiment

As shown in FIG. 8, in a lens barrel 10-3 according to the thirdembodiment, each of two mount projections 12 b are arranged on outsideof the long sides in a cross-section of the inner opening site 40 a ofthe mirror box 40. This configuration results in no exposure of themount projection 12 b on the inside of the opening site 40 a. Otherconfiguration and effects in the present embodiment is same as in theabove-described first embodiment.

Forth Embodiment

As shown in FIG. 9, in a lens barrel 10-4 according to the forthembodiment, the diameters of the inner circumferences of the barrel-sidemount projection 12 c and the cylindrical stiffened member 16 aredesigned equal to or longer than the length of the diagonal line of theinner opening site 40 a of the mirror box 40. Also, both of abarrel-side mount projection 12 c and a cylindrical stiffened member 16are designed not to be exposed on the inside of the inner opening site40 a. Other configuration and effects in the present embodiment is sameas in the above-described first embodiment.

Fifth Embodiment

As shown in FIG. 10, in a lens barrel 10-5 according to the fifthembodiment, a barrel-side mount projection 12 is arranged similar tothat in the first embodiment. Each of two electric contact holdingmembers 70 a and 70 b is arranged on the outside of the long sides ofthe cross-section of the inner opening site 40 a in the mirror box 40.The outer circumferences of electric contact holding members 70 a and 70b have barrel-side electric contact groups 72 a and 72 b respectively.

In the present embodiment, the number of the contact points at each ofthe electric contact groups 72 a and 72 b placed on the each of theelectric contact holding members 70 a and 70 b can be reduced since theelectric contact groups 72 a and 72 b are divided into two to exchangesignals between the lens barrel 10-5 and the camera body. As a result,the length in the circumferential direction can be reduced in eachelectric contact group 72 a and 72 b, and they can be arranged in asmaller space. Further, it results in increasing the flexibility indesign regarding the space between the electric contact groups 72 a and72 b and becoming easier to arrange each of the electric contact holdingmembers 70 a and 70 b to avoid the inner opening site 40 a of the mirrorbox 40.

Further, the arrangement to separate the electric contact groups 72 aand 72 b each other reduces interference between contacts, resulting inimproving S/N ratio. For example, an electromagnetic ray may easilyoccur at a contact point for electric power supply Where relativelylarge electric current passes. It can reduce an electric signal noise ata contact point for signal to separate a contact point for electricpower supply from that for signal. Other configuration and effects inthe present embodiment is same as in the above-described firstembodiment. Note that the electric contact holding member where electriccontact groups are placed is divided into four so that each can bearranged at the outside of four lines of the inner opening part 40 a ofthe mirror box 40 respectively.

Other Embodiments

The following conversion is possible in each embodiment.

(1) As shown in FIG. 4C, the mount projections 12 are described in theexample to arrange all of them to avoid four corners 11 a to 11 d of thelight flux L, but it is acceptable to arrange the mount projections 12to avoid some of four corners 11 a to 11 d. In this case, effects ofcatoptric light can be reduced as well.

(2) In the embodiment shown in FIG. 8, the mount projections 12 arearranged above and below the opening site 40 a, but it is acceptable toarrange them on the left and right of the opening site 40 a. Also, fourmount projections 12 can be arranged on the left, right, top and bottomof the opening site 40 a. It is also acceptable to provideconvexo-concave on the surface of the mount projections 12 for furtherprevention of reflection on the mount projections 12.

(3) Each embodiment described above is an example to apply theconfiguration of the present invention in a lens barrel, but it is alsopossible to apply the invention in a camera system holding such a lensbarrel, a video camera, and a TV camera, and other imaging equipments.

Note that the above-described embodiments can be used in combination,but detailed explanation is omitted here. Also, the invention is notlimited to the embodiments explained above.

What is claimed is:
 1. A lens barrel comprising a barrel holding anoptical system, a barrel-side mount to fit said barrel to a photographicdevice, and two or more barrel-side electric contact groups, whereinsaid photographic device comprises an imaging unit to take an image, anumber of said barrel-side mounts are present, each of said barrel-sideelectric contact groups includes two or more electric contact points andis placed with a space between each other barrel-side electric contactgroups, each of said barrel-side electric contact groups is placed on acircumference with a diameter shorter than a diagonal line of arectangular opening of a camera body and each of said barrel-sideelectric contact groups is arranged in a position to avoid all cornersof said rectangular opening and at an outside of side lines of saidrectangular opening.
 2. The lens barrel as set forth in claim 1comprising a barrel-side fitting plane placed parallel to said imagingunit, said barrel-side electric contact groups being placed between saidbarrel-side fitting plane and said imaging unit.
 3. The lens barrel asset forth in claim 1, wherein said imaging unit comprises a rectangularimaging plane, and said barrel-side electric contact groups are placedto avoid corners of said rectangular imaging plane.
 4. The lens barrelas set forth in claim 3, wherein said barrel-side electric contactgroups are placed corresponding to two opposite sides of saidrectangular imaging plane.
 5. The lens barrel as set forth in claim 3,wherein said barrel-side electric contact group is formed along a circlewith a larger diameter than the length of diagonal line of saidrectangular imaging plane.
 6. The lens barrel as set forth in claim 1,wherein one of said barrel-side electric contact groups includes a firstcontact point to provide necessary electricity for controlling the lensbarrel, and another one of said barrel-side electric contact groupsincludes a second contact point to provide at least either of necessarydetection signal and control signal for controlling the lens barrel. 7.A lens barrel comprising a barrel holding an optical system, abarrel-side mount to fit said barrel to a photographic device, and twoor more barrel-side electric contact groups, wherein each of saidbarrel-side electric contact groups includes two or more barrel-sideelectric contact points, said photographic device comprises an imagingunit to take an image, said barrel-side mount is placed between saidbarrel-side electric contact points, each of said barrel-side electriccontact groups is placed on a circumference with a diameter shorter thana diagonal line of a rectangular opening of a camera body, and each ofsaid barrel-side electric contact groups is arranged in a position toavoid all corners of said rectangular opening and at an outside of sidelines of said rectangular opening.
 8. The lens barrel as set forth inclaim 7, comprising a barrel-side fitting plane placed parallel to saidimaging unit, wherein said barrel-side electric contact points areplaced between said barrel-side fitting plane and said imaging unit. 9.The lens barrel as set forth in claim 7, wherein said imaging unitcomprises a rectangular imaging plane, and the barrel-side electriccontact points are placed to avoid corners of said rectangular imagingplane.
 10. The lens barrel as set forth in claim 9, wherein thebarrel-side electric contact points are placed corresponding to twoopposite sides of said rectangular imaging plane.
 11. The lens barrel asset forth in claim 9, wherein said barrel-side electric contact pointsare formed along a circle with a larger diameter than the length ofdiagonal line of said rectangular imaging plane.
 12. The lens barrel asset forth in claim 7, wherein one of said barrel-side electric contactpoints includes a first contact point to provide necessary electricityfor controlling the lens barrel, and another one of said barrel-sideelectric contact points includes a second contact point to provide atleast either of necessary detection signal and control signal forcontrolling the lens barrel.
 13. A photographic device comprising animaging unit to take an image by an optical system, a photographicdevice-side mount to fit a lens barrel to said photographic device, andtwo or more photographic device-side electric contact groups, whereinsaid lens barrel has an optical system to form an image on said imagingplane, each of said electric contact groups has two or more contactpoints, and is placed with a space between each other photographicdevice-side electric contact groups, each of said photographicdevice-side electric contact groups is placed on a circumference with adiameter shorter than a diagonal line of a rectangular opening of acamera body, and each of said photographic device-side electric contactgroups is arranged in a position to avoid all corners of saidrectangular opening and at an outside of side lines of said rectangularopening.
 14. The photographic device as set forth in claim 13,comprising a photographic device-side fitting plane placed parallel tosaid imaging unit, wherein said photographic device-side electriccontact groups are placed between said photographic device-side fittingplane and said imaging unit.
 15. The photographic device as set forth inclaim 13, wherein said imaging unit comprises a rectangular imagingplane, and said photographic device-side electric contact groups isplaced to avoid corners of said rectangular imaging plane.
 16. Thephotographic device as set forth in claim 13, wherein said lens barrelincludes barrel-side electric contact groups electrically connected withsaid photographic device-side electric contact groups.
 17. Aphotographic device comprising an imaging unit to take an image by anoptical system, a photographic device-side mount to fit a lens barrel tothe photographic device, and two or more photographic device-sideelectric contact groups, wherein each of said photographic device-sideelectric contact groups includes two or more photographic device-sideelectric contact points, said lens barrel has said optical system toform an image on said imaging plane, said photographic device-side mountis placed between said photographic device-side electric contact points,each of said photographic device-side electric contact groups is placedon a circumference with a diameter shorter than a diagonal line of arectangular opening of a camera body, and each of said photographicdevice-side electric contact groups is arranged in a position to avoidall corners of said rectangular opening and at an outside of side linesof said rectangular opening.
 18. The photographic device as set forth inclaim 17, wherein a photographic device-side fitting plane is placedparallel to said imaging unit, and said photographic device-sideelectric contact points are placed between said photographic device-sidefitting plane and said imaging unit.
 19. The lens barrel as set forth inclaim 17, wherein said imaging unit comprises a rectangular imagingplane, and said photographic device-side electric contact points areplaced to avoid corners of said rectangular imaging plane.
 20. Thephotographic device as set forth in claim 17, wherein said lens barrelincludes barrel-side electric contact points electrically connected withsaid photographic device-side electric contact points.
 21. A productionmethod of a lens barrel comprising the steps of: providing a barrelholding an optical system, providing multiple barrel-side mounts on saidbarrel to fit a photographic device having an imaging unit to take animage formed by said optical system, and providing two or morebarrel-side electric contact groups, each of which is placed with aspace between each other and has two or more barrel-side electriccontact points, each of said barrel-side electric contact groups isplaced on a circumference with a diameter shorter than a diagonal lineof a rectangular opening of a camera body, and each of said barrel-sideelectric contact groups is arranged in a position to avoid all cornersof said rectangular opening and at an outside of side lines of saidrectangular opening.
 22. A production method of a lens barrel comprisingthe steps of: providing a barrel holding an optical system, providing abarrel-side mount on said barrel to fit a photographic device having animaging unit to take an image formed by said optical system, andproviding two or more barrel-side electric contact groups, each of whichhas two or more barrel-side electric contact points, each of saidbarrel-side electric contact groups is placed on a circumference with adiameter shorter than a diagonal line of a rectangular opening of acamera body, and each of said barrel-side electric contact groups isarranged in a position to avoid all corners of said rectangular openingand at an outside of side lines of said rectangular opening.
 23. Aproduction method of a photographic device comprising the steps of:providing an imaging unit to take an image formed by an optical system,providing multiple photographic device-side mounts to fit a lens barrel,and providing two or more photographic device-side electric contactgroups, each of which is placed with a space between each other and hastwo or more electric contact points, each of said photographicdevice-side electric contact groups is placed on a circumference with adiameter shorter than a diagonal line of a rectangular opening of acamera body, and each of said photographic device-side electric contactgroups is arranged in a position to avoid all corners of saidrectangular opening and at an outside of side lines of said rectangularopening.
 24. A production method of a photographic device comprising thesteps of: providing an imaging unit to take an image formed by anoptical system, providing a photographic device-side mount to fit a lensbarrel, and providing two or more photographic device-side electriccontact groups, each of which has two or more photographic device-sideelectric contact points, said photographic device-side mount beingplaced between said photographic device-side electric contact points,each of said photographic device-side electric contact groups is placedon a circumference with a diameter shorter than a diagonal line of arectangular opening of a camera body, and each of said photographicdevice-side electric contact groups is arranged in a position to avoidall corners of said rectangular opening and at an outside of side linesof said rectangular opening.